In general, shaving razors of the wet shave type include a cartridge or blade unit with at least one blade with a cutting edge which is moved across the surface of the skin being shaved by means of a handle to which the cartridge is attached. The cartridge may be mounted detachably on the handle to enable the cartridge to be replaced by a fresh cartridge when the blade sharpness has diminished to an unsatisfactory level, or it may be attached permanently to the handle with the intention that the entire razor be discarded when the blade or blades have become dulled. Razor cartridges usually include a guard which contacts the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s) during shaving. The cap and guard aid in establishing the so-called “shaving geometry”, i.e., the parameters which determine the blade orientation and position relative to the skin during shaving, which in turn have a strong influence on the shaving performance and efficacy of the razor. The guard may be generally rigid, for example formed integrally with a frame or platform structure which provides a support for the blades.
In the use of shaving razors of the wet shave type, factors such as frictional drag of the razor across the skin, force needed to sever hairs, and irritation or pre-existing skin damage can create a degree of shaving discomfort. Shaving aids, e.g., a lubricant, whisker softener, razor cleanser, medicinal agent, cosmetic agent or combination thereof, have been incorporated into razors, for example by incorporating a shaving aid into one or more extruded or molded polymeric components of the razor. Such shaving aid composites may be mounted on the cap or guard structures of the razor cartridge. Upon exposure to water, water-soluble shaving aid leaches from the composite onto the skin and the composite tends to swell.
The shaving aid composites must be positively secured for effective dispensing throughout the useful shaving life of the razor. Forces during shaving may contribute to loosening of the shaving aid components from the cartridge. Numerous extruded or molded shaving aid components have been developed which are secured to the shaving razor cartridge with adhesives. These arrangements have been unsatisfactory for certain applications. Adhesives are typically a poor choice for several reasons. Adhesives are difficult to work with from a manufacturing perspective and are also susceptible to changes in heat and humidity. In certain countries, shaving razors are exposed to constant high levels of heat and humidity during shipment and storage. These levels of heat and humidity can adversely affect the adhesive properties such that the lubrication component is no longer secured. Various press-fit type designs have also been developed to secure the shaving aid component to the cartridge of the shaving razor. The various press-fit type designs have also proven to be ineffective in certain applications. Press-fit designs rely on a significant amount of force to be applied to the shaving aid composite in order to properly secure the shaving aid composite within the housing, which may cause the shaving aid composite to break or fracture. These designs are also not very effective because they do not accommodate for changing forces resulting from the shaving aid composite swelling and expanding. These cartridge designs also rely on an increased surface contact area with the shaving aid composite to better secure the shaving aid composite to the cartridge, which limits the cartridge design, such as the size of the cartridge and the placement of the blade(s).